Detect whether ccache is available to bisect.

ccache will save time during a bisect but it may not always be availble.
Teach bisect-runner.pl to only use it if it is available.

diff --git a/Porting/bisect-runner.pl b/Porting/bisect-runner.pl
index 5896d3a..fea722b 100755 (executable)
--- a/Porting/bisect-runner.pl
+++ b/Porting/bisect-runner.pl
@@ -53,7 +53,7 @@ my %defines =
     (
      usedevel => '',
      optimize => '-g',
-     cc => 'ccache cc',
+     cc => (`ccache --version`, $?) ? 'cc' : 'ccache cc',
      ld => 'cc',
      ($linux64 ? (libpth => \@paths) : ()),
     );